The advent of rotary forging machines has made it possible to expeditiously and accurately form tubular articles, such as track roller shafts. The machine essentially functions to reduce the cross-sectional area or shapes of billets, bars, and tubes by repeated radial strokes with a pair of opposed die parts. The workpiece is fed longitudinally through the die and rotated simultaneously therein to force the material into the desired shape by a series of short, rapid strokes of the die parts. During the forging of a track roller shaft, for example, an expandable chuck of the machine is clamped onto an end of a pre-formed shell portion of the shaft and the chuck is moved longitudinally towards the die and simultaneously rotated, whereby an end of the shaft may be reduced to a predetermined diameter.
Gripping of the shaft with the chuck tends to deform the shaft, thus requiring subsequent machining thereof. In addition, slippage can occur between the rotating chuck and the shaft, thus requiring a prolonged cycle time for forging the shaft into the desired configuration. Such relative slippage can occur both in a rotational direction as well as axially. For example, in one application, a cycle time of approximately 110 seconds was required to form the end of the shaft into the desired configuration. In contrast thereto, the pusher block and method of this invention has been found to reduce such cycle time to approximately 47 seconds. Another problem with conventional forging machines and methods of this type is that securance of the shaft within the chuck required longitudinal movement of the workpiece a substantial distance, thus adding to the above cycle time.
The present invention is directed to overcoming one or more of the problems as set forth above.